MCTP1 promotes SNAI1-driven neuroendocrine differentiation and epithelial-to-mesenchymal transition of prostate cancer enhancement by ZBTB46/FOXA2/HIF1A

Abstract Background Prostate cancer (PCa) patients with bone metastases frequently exhibit abnormal calcium homeostasis. However, the molecular mechanisms underlying bone metastasis mediated by activated calcium transport signaling remain unclear. Our results showed that androgen deprivation therapy (ADT) of PCa upregulates a calcium sensor transmembrane protein, the multiple C2 domains transmembrane protein 1 (MCTP1), which is upregulated by hypoxia-induced ZBTB46/FOXA2/HIF1A signaling and is associated with SNAI1-driven neuroendocrine (NE) differentiation (NED) and epithelial-to-mesenchymal transition (EMT) in PCa. Methods Hypoxia induced interactions between ZBTB46, HIF1A, and FOXA2 were confirmed by immunoprecipitation (IP)-Western Blot (WB). Correlation between MCTP1 and ZBTB46/FOXA2/HIF1A complexes was analyzed by immunohistochemical (IHC) staining in consecutive tissue sections of PCa tissue microarray (TMA) comprising primary PCa and small cell PCa (SCPC) samples. The regulatory network between MCTP1 and the hypoxia-induced ZBTB46/FOXA2/HIF1A axis was investigated by chromatin IP (ChIP)-Seq analysis, ChIP assay, and promoter reporter assays. The effect of MCTP1 on SNAI1 expression driving NED and EMT in PCa was identified in PCa cell lines using mimic hypoxia, ADT, or long-term androgen receptor (AR) antagonist culture systems. Activation of the MCTP1-mediated calcium-related pathway induces SNAI1-driven NED and aggressive progression of PCa under hypoxic conditions was examined by Fluo-8 AM staining combined with flow cytometry, migration, invasion, and xenograft model validation. Results MCTP1 is highly expressed in advanced PCa tissues and is associated with ZBTB46/FOXA2/HIF1A abundance. Upregulation of MCTP1 enhances SNAI1-mediated cell migration and EMT responses and is associated with hypoxia-driven NED in PCa after ADT. Mechanistically, hypoxia enhances the MCTP1-mediated calcium/AKT pathway to stabilize SNAI1 in PCa to promote EMT and NED by increasing the SNAI1-driven expression of EMT and NE markers. MCTP1 knockdown abrogated hypoxia-enhanced EMT and NED by reducing calcium/AKT pathway-driven SNAI1 expression. Conclusions Our study shows the molecular mechanism by which hypoxia-associated ZBTB46/FOXA2/HIF1A transcription factor interaction upregulates the calcium sensor transmembrane protein MCTP1 in ADT-resistant PCa, and explores how MCTP1 promotes NED and EMT in PCa by upregulating SNAI1-driven EMT and NE markers.